I honestly have not interacted with Retroarch's devs enough to have an opinion on them. I do know Squarepusher has made it well known he disapproves of emulators that charge money and his reasons for that belief. Personally I don't agree with aome of what he says but I don't agree with some of what a lot of people say and I don't think any less of them for having differing opinions from me either.

As far as RetroArch (the program) goes...Personally I tend have more issues with the UI of retroarch (the menu systems ingame and out) then with the performance of any core. Well at least compared to the exact same program the core is based on.